The purpose of this work is to study the enzymes of the chitin (N- acetylglucosamine polymer) pathway in houseflies. In particular, glucosamine phosphate isomerase from the adult housefly is being studied in detail. This will include purification to homogeneity and subsequent study of subunit interaction and binding sites for allosteric ligands. Enzymes of the chitin pathway in other developmental stages of the housefly (eggs, larvae, and pupae) are also under investigation. Elucidation of the hormonal and metabolic control of chitin pathway enzymes is a primary objective. If specific inhibitors of these anabolic enzymes can be found, these compounds may be useful as selective insecticides harmless to vertebrates and the environment.